{"id":"F2005L02825","name":"AD/B727/197 - MLG Wheel Well Pressure Floor - 2","slug":"ad-b727-197-mlg-wheel-well-pressure-floor-2","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":37760,"registerId":"commonwealth-F2005L02825-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 727 Series Aeroplanes","sectionType":"division","heading":"Boeing 727 Series Aeroplanes","content":"### Boeing 727 Series Aeroplanes\n\n| AD/B727/197 | MLG Wheel Well Pressure Floor - 2 | 11/2005 |\n| ----------- | --------------------------------- | ------- |\n\n| Applicability: | Model 727 series aircraft.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |\n| -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | Action in accordance with the technical requirements of FAA AD 91-22-08 Amdt39-8068.Note: Boeing Service Bulletin 727-53A0124 Revision 3, or later FAA approved revision, refer.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |\n| Compliance:    | Unless the initial inspections have been accomplished, and for all other requirements, as specified in the Requirement document; with a revised effective date of 27 October 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n|                | This Airworthiness Directive becomes effective on 27 October 2005.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| Background:    | This Directive has been issued to re-introduce additional FAA requirements for the main landing gear wheel well pressure floor. FAA AD 91-22-08 was prompted by several reports of cracking in areas adjacent to a previously installed modification and not required to be inspected. This Directive requires additional inspections of aircraft on which the modification has been installed, requires inspections of additional aircraft on which the modification was incorporated in production, requires an expanded inspection area for unmodified aircraft, reduces the initial inspection threshold, and limits the time that blind rivets may be used. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n15 September 2005","sortOrder":0},{"sectionNumber":"AD/B727/197","sectionType":"part","heading":"AD/B727/197","content":"## AD/B727/197","sortOrder":1},{"sectionNumber":"MLG Wheel Well Pressure Floor - 2","sectionType":"part","heading":"MLG Wheel Well Pressure Floor - 2","content":"## MLG Wheel Well Pressure Floor - 2","sortOrder":2},{"sectionNumber":"11/2005","sectionType":"part","heading":"11/2005","content":"## 11/2005","sortOrder":3}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope: addressing a specific structural fatigue issue in a specific aircraft type (Boeing 727). It does not expand beyond aviation safety maintenance requirements."},"complexity_factors":["Short document (approximately 250 words of substantive content)","Only 1 defined term implicitly used ('MLG' — Main Landing Gear)","Single cross-reference to external technical document (FAA AD 91-22-08)","Single cross-reference to manufacturer service bulletin (Boeing SB 727-53A0124)","Simple conditional structure: applicability based on aircraft model and modification status","No nested exceptions or complex legislative machinery","Operational rather than legislative complexity — the technical aviation maintenance requirements are detailed in the referenced FAA document, not in this instrument itself"],"plain_english_summary":"This AD mandates inspections and maintenance of the main landing gear wheel‑well pressure floor on Boeing 727 series aircraft operating in Australia after cracks were found near a prior modification. It affects both modified and unmodified airframes, shortens the initial inspection threshold, limits ongoing use of blind rivets, and relies on FAA AD 91‑22‑08 and a Boeing service bulletin for technical procedures. Effective 27 October 2005."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":true,"description":"This AD increases the scope of inspection and corrective actions compared with the prior requirement. It expands the inspection area for unmodified aircraft, adds aircraft that had the modification installed in production to the inspection pool, reduces the time before the first inspection (shorter initial threshold), and introduces a time limit on the use of blind rivets. In combination these steps extend coverage beyond the original, narrower inspection regime and impose additional maintenance obligations on operators."},"complexity_factors":["Cross-reference to FAA AD 91-22-08 (Amendment 39-8068) rather than containing full technical procedures in the national instrument","Cross-reference to Boeing Service Bulletin 727-53A0124 Revision 3 (or later FAA‑approved revision) for technical detail","Different requirements depending on aircraft status: modified in service, modified in production, or unmodified (expanded inspection area vs those already modified)","Multiple conditional changes: reduced initial inspection threshold, expanded inspection area, and limitation on blind rivets","Implicit dependence on subsequent technical documents (FAA AD and Service Bulletin) for exact inspection panels, intervals and repair instructions"],"plain_english_summary":"**What this instrument does (mechanically)\n\n- Applies to: All Boeing 727 series aircraft.\n- Mandatory action: Requires operators to carry out inspections and any necessary corrective work on the main landing gear (MLG) wheel well pressure floor in accordance with FAA Airworthiness Directive (AD) 91-22-08 (Amendment 39-8068) and Boeing Service Bulletin 727-53A0124 Revision 3 (or a later FAA‑approved revision).\n- Effective date: The AD became effective on 27 October 2005; operators must comply from that date unless the initial inspections were already completed under the earlier requirement.\n\nSummary of the technical change\n\n- Inspections expanded: The inspection area for unmodified aircraft is larger than previously required.\n- More aircraft covered: Aircraft that incorporated a specified modification in production are now required to be inspected (in addition to aircraft on which the modification was later installed).\n- Shorter inspection interval: The time before the first inspection (initial threshold) has been reduced compared with the prior requirement.\n- Blind rivet limit: The AD imposes a time limit on how long blind (pop) rivets may be used in the affected structure.\n\nOfficial rationale (what the regulator says)\n\n- The AD was issued after reports of cracking adjacent to a previously installed modification in the wheel well pressure floor. The extra inspections and limits are intended to detect and correct cracking that was previously not inspected.\n\nWho this affects and what they must do\n\n- Who pays: Aircraft owners and operators of Boeing 727s pay for inspections, any follow‑up inspections, repairs, and any downtime required to perform them.\n- Who decides: The Civil Aviation Safety Authority (CASA) enforces the AD; compliance must follow the cited FAA AD and Boeing Service Bulletin (or later FAA‑approved revisions). Operators may use later FAA‑approved revisions of the service bulletin.\n- Required behaviour: Operators must schedule and perform the specified inspections, document compliance, and carry out repairs or modifications stated in the FAA AD/Boeing SB when cracking or non‑conformance is found.\n\nCosts, incentives and trade‑offs (practical implications)\n\n- Direct costs: Inspection labour, non‑destructive testing, parts and structural repairs, and aircraft downtime. These are borne by operators (airlines, lessors, or owners).\n- Incentives: Early detection of cracking reduces the risk of in‑service structural failure; however, the shorter inspection threshold increases near‑term maintenance costs and may create concentrated short‑term demand for inspectors and parts.\n- Opportunity cost: Time and resources spent on these inspections reduce capacity for other maintenance tasks and may cause scheduling or revenue impacts for operators.\n- Implementation risks: Availability of appropriately trained maintenance personnel, access to FAA‑approved repair methods, and supply of authorised parts/fasteners (including approved rivet types). If blind rivets are restricted, operators may need alternative fastening and associated work instructions.\n- Compliance discretion and substitution: The AD requires compliance with the FAA AD and Boeing SB. Operators can adopt later FAA‑approved revisions (so an FAA revision that relaxes or tightens requirements will change obligations). There is limited room for alternative means of compliance unless explicitly approved by the regulator.\n\nTrade‑offs CASA explicitly created\n\n- Safety vs cost: The regulator tightened inspection coverage and reduced the inspection interval to find cracks earlier, shifting higher immediate maintenance costs to operators to reduce structural risk in service.\n\nWhere to look for the technical detail\n\n- The AD references FAA AD 91-22-08 Amendment 39-8068 and Boeing Service Bulletin 727-53A0124 Revision 3 (or later FAA‑approved revision) for inspection methods, intervals, inspection panels/areas, and repair instructions. Operators should follow those documents for the exact inspection procedures, thresholds, and corrective-action criteria.\n\nSource references in the instrument\n\n- Requirement: action in accordance with FAA AD 91-22-08 (Amdt 39-8068) and Boeing SB 727-53A0124 Rev 3 or later FAA‑approved revision.\n- Compliance clause: effective 27 October 2005; unless initial inspections already done, follow the Requirement document.\n- Background: issued after reports of cracking adjacent to a previous modification; expands inspection coverage, reduces initial thresholds, and limits blind rivet usage.\n\nPlain practical takeaway\n\n- If you operate a Boeing 727, you must follow the specified FAA AD and Boeing service bulletin to inspect the MLG wheel well pressure floor, repair any cracking found, and stop relying on blind rivets beyond the period allowed. Expect inspection costs, potential repairs and aircraft downtime; the measures are intended to find and fix cracking that earlier requirements missed.**"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b727-197-mlg-wheel-well-pressure-floor-2","history":"/api/acts/ad-b727-197-mlg-wheel-well-pressure-floor-2/history","analysis":"/api/acts/ad-b727-197-mlg-wheel-well-pressure-floor-2/analysis","conflicts":"/api/acts/ad-b727-197-mlg-wheel-well-pressure-floor-2/conflicts","importantCases":"/api/acts/ad-b727-197-mlg-wheel-well-pressure-floor-2/important-cases","documents":"/api/acts/ad-b727-197-mlg-wheel-well-pressure-floor-2/documents"}}